1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * drivers/watchdog/ar7_wdt.c 4 * 5 * Copyright (C) 2007 Nicolas Thill <nico@openwrt.org> 6 * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org> 7 * 8 * Some code taken from: 9 * National Semiconductor SCx200 Watchdog support 10 * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> 11 * 12 */ 13 14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 15 16 #include <linux/module.h> 17 #include <linux/moduleparam.h> 18 #include <linux/errno.h> 19 #include <linux/miscdevice.h> 20 #include <linux/platform_device.h> 21 #include <linux/watchdog.h> 22 #include <linux/fs.h> 23 #include <linux/ioport.h> 24 #include <linux/io.h> 25 #include <linux/uaccess.h> 26 #include <linux/clk.h> 27 28 #include <asm/addrspace.h> 29 #include <asm/mach-ar7/ar7.h> 30 31 #define LONGNAME "TI AR7 Watchdog Timer" 32 33 MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>"); 34 MODULE_DESCRIPTION(LONGNAME); 35 MODULE_LICENSE("GPL"); 36 37 static int margin = 60; 38 module_param(margin, int, 0); 39 MODULE_PARM_DESC(margin, "Watchdog margin in seconds"); 40 41 static bool nowayout = WATCHDOG_NOWAYOUT; 42 module_param(nowayout, bool, 0); 43 MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close"); 44 45 #define READ_REG(x) readl((void __iomem *)&(x)) 46 #define WRITE_REG(x, v) writel((v), (void __iomem *)&(x)) 47 48 struct ar7_wdt { 49 u32 kick_lock; 50 u32 kick; 51 u32 change_lock; 52 u32 change; 53 u32 disable_lock; 54 u32 disable; 55 u32 prescale_lock; 56 u32 prescale; 57 }; 58 59 static unsigned long wdt_is_open; 60 static unsigned expect_close; 61 static DEFINE_SPINLOCK(wdt_lock); 62 63 /* XXX currently fixed, allows max margin ~68.72 secs */ 64 #define prescale_value 0xffff 65 66 /* Resource of the WDT registers */ 67 static struct resource *ar7_regs_wdt; 68 /* Pointer to the remapped WDT IO space */ 69 static struct ar7_wdt *ar7_wdt; 70 71 static struct clk *vbus_clk; 72 73 static void ar7_wdt_kick(u32 value) 74 { 75 WRITE_REG(ar7_wdt->kick_lock, 0x5555); 76 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) { 77 WRITE_REG(ar7_wdt->kick_lock, 0xaaaa); 78 if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) { 79 WRITE_REG(ar7_wdt->kick, value); 80 return; 81 } 82 } 83 pr_err("failed to unlock WDT kick reg\n"); 84 } 85 86 static void ar7_wdt_prescale(u32 value) 87 { 88 WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a); 89 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) { 90 WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5); 91 if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) { 92 WRITE_REG(ar7_wdt->prescale, value); 93 return; 94 } 95 } 96 pr_err("failed to unlock WDT prescale reg\n"); 97 } 98 99 static void ar7_wdt_change(u32 value) 100 { 101 WRITE_REG(ar7_wdt->change_lock, 0x6666); 102 if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) { 103 WRITE_REG(ar7_wdt->change_lock, 0xbbbb); 104 if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) { 105 WRITE_REG(ar7_wdt->change, value); 106 return; 107 } 108 } 109 pr_err("failed to unlock WDT change reg\n"); 110 } 111 112 static void ar7_wdt_disable(u32 value) 113 { 114 WRITE_REG(ar7_wdt->disable_lock, 0x7777); 115 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) { 116 WRITE_REG(ar7_wdt->disable_lock, 0xcccc); 117 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) { 118 WRITE_REG(ar7_wdt->disable_lock, 0xdddd); 119 if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) { 120 WRITE_REG(ar7_wdt->disable, value); 121 return; 122 } 123 } 124 } 125 pr_err("failed to unlock WDT disable reg\n"); 126 } 127 128 static void ar7_wdt_update_margin(int new_margin) 129 { 130 u32 change; 131 u32 vbus_rate; 132 133 vbus_rate = clk_get_rate(vbus_clk); 134 change = new_margin * (vbus_rate / prescale_value); 135 if (change < 1) 136 change = 1; 137 if (change > 0xffff) 138 change = 0xffff; 139 ar7_wdt_change(change); 140 margin = change * prescale_value / vbus_rate; 141 pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n", 142 margin, prescale_value, change, vbus_rate); 143 } 144 145 static void ar7_wdt_enable_wdt(void) 146 { 147 pr_debug("enabling watchdog timer\n"); 148 ar7_wdt_disable(1); 149 ar7_wdt_kick(1); 150 } 151 152 static void ar7_wdt_disable_wdt(void) 153 { 154 pr_debug("disabling watchdog timer\n"); 155 ar7_wdt_disable(0); 156 } 157 158 static int ar7_wdt_open(struct inode *inode, struct file *file) 159 { 160 /* only allow one at a time */ 161 if (test_and_set_bit(0, &wdt_is_open)) 162 return -EBUSY; 163 ar7_wdt_enable_wdt(); 164 expect_close = 0; 165 166 return stream_open(inode, file); 167 } 168 169 static int ar7_wdt_release(struct inode *inode, struct file *file) 170 { 171 if (!expect_close) 172 pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n"); 173 else if (!nowayout) 174 ar7_wdt_disable_wdt(); 175 clear_bit(0, &wdt_is_open); 176 return 0; 177 } 178 179 static ssize_t ar7_wdt_write(struct file *file, const char *data, 180 size_t len, loff_t *ppos) 181 { 182 /* check for a magic close character */ 183 if (len) { 184 size_t i; 185 186 spin_lock(&wdt_lock); 187 ar7_wdt_kick(1); 188 spin_unlock(&wdt_lock); 189 190 expect_close = 0; 191 for (i = 0; i < len; ++i) { 192 char c; 193 if (get_user(c, data + i)) 194 return -EFAULT; 195 if (c == 'V') 196 expect_close = 1; 197 } 198 199 } 200 return len; 201 } 202 203 static long ar7_wdt_ioctl(struct file *file, 204 unsigned int cmd, unsigned long arg) 205 { 206 static const struct watchdog_info ident = { 207 .identity = LONGNAME, 208 .firmware_version = 1, 209 .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | 210 WDIOF_MAGICCLOSE), 211 }; 212 int new_margin; 213 214 switch (cmd) { 215 case WDIOC_GETSUPPORT: 216 if (copy_to_user((struct watchdog_info *)arg, &ident, 217 sizeof(ident))) 218 return -EFAULT; 219 return 0; 220 case WDIOC_GETSTATUS: 221 case WDIOC_GETBOOTSTATUS: 222 if (put_user(0, (int *)arg)) 223 return -EFAULT; 224 return 0; 225 case WDIOC_KEEPALIVE: 226 ar7_wdt_kick(1); 227 return 0; 228 case WDIOC_SETTIMEOUT: 229 if (get_user(new_margin, (int *)arg)) 230 return -EFAULT; 231 if (new_margin < 1) 232 return -EINVAL; 233 234 spin_lock(&wdt_lock); 235 ar7_wdt_update_margin(new_margin); 236 ar7_wdt_kick(1); 237 spin_unlock(&wdt_lock); 238 fallthrough; 239 case WDIOC_GETTIMEOUT: 240 if (put_user(margin, (int *)arg)) 241 return -EFAULT; 242 return 0; 243 default: 244 return -ENOTTY; 245 } 246 } 247 248 static const struct file_operations ar7_wdt_fops = { 249 .owner = THIS_MODULE, 250 .write = ar7_wdt_write, 251 .unlocked_ioctl = ar7_wdt_ioctl, 252 .compat_ioctl = compat_ptr_ioctl, 253 .open = ar7_wdt_open, 254 .release = ar7_wdt_release, 255 .llseek = no_llseek, 256 }; 257 258 static struct miscdevice ar7_wdt_miscdev = { 259 .minor = WATCHDOG_MINOR, 260 .name = "watchdog", 261 .fops = &ar7_wdt_fops, 262 }; 263 264 static int ar7_wdt_probe(struct platform_device *pdev) 265 { 266 int rc; 267 268 ar7_regs_wdt = 269 platform_get_resource_byname(pdev, IORESOURCE_MEM, "regs"); 270 ar7_wdt = devm_ioremap_resource(&pdev->dev, ar7_regs_wdt); 271 if (IS_ERR(ar7_wdt)) 272 return PTR_ERR(ar7_wdt); 273 274 vbus_clk = clk_get(NULL, "vbus"); 275 if (IS_ERR(vbus_clk)) { 276 pr_err("could not get vbus clock\n"); 277 return PTR_ERR(vbus_clk); 278 } 279 280 ar7_wdt_disable_wdt(); 281 ar7_wdt_prescale(prescale_value); 282 ar7_wdt_update_margin(margin); 283 284 rc = misc_register(&ar7_wdt_miscdev); 285 if (rc) { 286 pr_err("unable to register misc device\n"); 287 goto out; 288 } 289 return 0; 290 291 out: 292 clk_put(vbus_clk); 293 vbus_clk = NULL; 294 return rc; 295 } 296 297 static int ar7_wdt_remove(struct platform_device *pdev) 298 { 299 misc_deregister(&ar7_wdt_miscdev); 300 clk_put(vbus_clk); 301 vbus_clk = NULL; 302 return 0; 303 } 304 305 static void ar7_wdt_shutdown(struct platform_device *pdev) 306 { 307 if (!nowayout) 308 ar7_wdt_disable_wdt(); 309 } 310 311 static struct platform_driver ar7_wdt_driver = { 312 .probe = ar7_wdt_probe, 313 .remove = ar7_wdt_remove, 314 .shutdown = ar7_wdt_shutdown, 315 .driver = { 316 .name = "ar7_wdt", 317 }, 318 }; 319 320 module_platform_driver(ar7_wdt_driver); 321